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The ionization structure of planetary nebulae. VII. New observations of the Ring NebulaNew optical spectrophotometric observations of emission-line intensities have been made in eight positions in the Ring Nebula corresponding to those observed previously with the Ultraviolet Explorer satellite; the total coverage is therefore 1400 to 7200 A. The intensities are in generally good agreement with those found previously in corresponding positions. The Oand Balmer continuum electron temperatures agree well on the average and, like the Nelectron temperatures, decrease with increasing distance from the central star. As found previously for the Ring Nebula and for other planetaries in this series, the lambda 4267 C 2 line intensity near the central star implies a Cabundance that is higher than that determined from the lambda 1906, 1909 C 3 lines. The discrepancy again decreases with increasing distance from the central star and vanishes from the outermost positions, again suggesting that the excitation mechanism from the lambda 4267 line is not understood. Standard equations used to correct for the existence of elements in other than the optically observable ionization stages give results that are consistent and in appropriate agreement with abundances calculated using UV lines. The rather high abundances of O, N, and C, and, to some extent N, indicate that some mixing of CNO processed material into the nebular shell may have occurred in the Ring Nebula.
Document ID
19880031882
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Barker, Timothy
(Wheaton College Norton, MA, United States)
Date Acquired
August 13, 2013
Publication Date
November 15, 1987
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 322
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
88A19109
Funding Number(s)
CONTRACT_GRANT: NSG-5376
Distribution Limits
Public
Copyright
Other

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